Abrasive disc holder



April 1969 R. R. CHENEY I 3,436,875

ABRAS I VE DI SC HOLDER Filed Aug. 5. 1966 a 72 ii? 78 5 INVENTOR. 540 /7 ,6 (#91/64 3,436,875 ABRASIVE DISC HOLDER Ralph R. Cheney, 501 E. Orangethorpe, Anaheim, Calif. 92801 Filed Aug. 5, 1966, Ser. No. 570,652 Int. Cl. B2411 9/06 US. Cl. 51-376 Claims ABSTRACT OF THE DISCLOSURE An abrasive disc holder means fo rotary sanding use comprising an arbor on which is a flexible generally frustoconical body, the base of the cone comprising a flat or slightly concave face urrounding a central hub which carries connecting means for securing the abrasive disc, said disc including complementary connecting means extending from its rear face to detachably engage the connecting means in or on the hub of the body of the holder.

This invention relates to abrasive disc holders primarily intended for industrial use in what are ordinarily termed sanding operations, even though the abrasive is generally of a harder material such as metallic grit. Such abrasive disc holders in general include an arbor on which is a flexible generally frusto-conical body, the base of the cone comprising a flat or slightly concave face surrounding a central hub which carries connecting means for securing the abrasive disc. The disc ordinarily includes complementary connecting mean extending from its rear face to detachably engage the connecting means in or on the hub of the body of the holder.

One type of holder presently in use includes a bayonet joint type of connector between the disc and the body of the holder. The disc being pressed against the hub and partially rotated so that complementary prongs and sockets will detachably interlock.

Another type of holder includes a hub having recesses formed therein to receive yielding detents which may be made of a plastic material, the recesses being formed entirely within the hub and therefore of relatively small overall area.

In both presently used forms described above, the connecting means between the abrasive disc and the hub of the holder provide the rotary drive for the disc so that a considerable strain is placed upon this connector. The result is that the connector will become worn and the discs will not be properly retained, or if the connector is so constructed as to retain the abrasive disc regardless of connector wear, the connector structure must be made so positive that removal and replacement of abrasive discs is relatively difficult.

It is an object of the present invention to provide an abrasive disc holder wherein the disc is held securely and will not become accidentally dislodged yet wherein it can be readily removed and a new disc secured to the holder.

Another object of the invention is to provide such a device wherei the disc and the holder are drivingly interlocked at point spa'ced radially outwardly from the hub proper and its connector to provide a greater rotational leverage connection between the disc and its supporting body.

The above and other objects will more fully appear from the following description in connection with the accompanying drawing:

FIG. 1 is a plan view of a mounted disc looking at the abrasive surface of the disc;

FIG. 2 is a side elevational view of the embodiment States Patent 0 'ice of FIG. 1 showing the supporting chuck in broken lines;

FIG. 3 is an enlarged sectional detail taken approximately on the line 3-3 of FIG. 1;

"FIG. 4 is a view similar to that of FIG. 3 with the holder and the disc attached connector portions in partially detached relationship;

FIG. 5 is a sectional detail of a different specific form;

FIG. 6 is a view similar to FIG. 5 with the interconnecting parts separated;

FIG. 7 is an exploded perspective view of the hub and connector shown in the embodiment of FIGS. 1 through There is illustrated in FIG. 2 a chuck 10 which is pref erably suitably driven by a electric motor which may be bench mounted or portable. In the chuck 10 is a spindle 12 which has mounted on its outer end a generally frustoconical body 14 and on whose base or outer face is an abrasive disc 16. The body 1'4 may be of rubber or a suitable plastic having the comparable resilient qualities.

As shown in FIG. 3 a hub 18 of rubber or plastic is embedded in the rubber body 14 and suitably vulcanized or otherwise attached thereto so that the hub and body will rotate as a unit. The hub has a relieved central portion 20, which as shown in FIG. 7, is defined by a squared socket having outwardly divergent walls. Obviously, the number of walls is not critical and the socket may if desired merely be made out of round rather than squared and still provide for rotation of the rubber and the body 14 together.

Mounted in the body 14 is a threaded spindle 22 which is also vulcanized or otherwise suitably secured in said body. The spindle extends outwardly through the hub 18 and terminates in the open central socket 20 of the hub. The spindle has a reduced portion 24 defining a shoulder 26. Outwardly from the shoulder is a tapered squared surface 28 which adjoins a nontapered squared surface 30 on the other or outer side of which end at the outer end of the spindle is a tapered squared surface 32.

Cooperating with the hub 18 and the outer end of the spindle 22 is a connector indicated generally at 34 which may be of a resilient plastic material. It includes a flange 36 and at least two inwardly extending connector prongs 38. In the drawing four of such prongs are illustrated and they are shown separated from each other. They are of sufiicient resilience to provide a snap connector in conjunction with the outer end portion of the spindle 22. The prongs 38 on their outer sides taper inwardly at an angle conforming generally to that of the divergent walls of the hub cavity or socket 20. The inner portion of each prong 38 has a straight portion 40 which normally is parallel to the axis of the spindle 22 and to the squared surface 30 of the outer end portion of the spindle. Inwardly from the straight portions 40 are inwardly tapered faces 42 which are at an angle conforming to the tapered squared portion 28 of the spindle 22. As shown in FIG. 4, when the connector 3 4 is pressed on the end of the spindle, the outermost tapered spindle surface 32 will be engaged by the ends of the prongs 38. Additional inward pressure on the connector 34 will cause the prongs to be sprung apart so they will slip over the spindle portion 30 and snap behind the inner tapered spindle portion 28.

The abrasive disc 16 is secured to the outer face of the connector flange 36 by suitable adhesives known in the art. The connector 34 is then snapped into the hub cavity or socket 20 and around the end of the spindle 22, the inherent resilience of the hub 18 holding the connector 34 securely in place. When the spindle 10 and the abrasive disc holder are rotated the squared shape of the hub cavity 20 and the group of prongs 28 will prevent relative rotation between the abrasive disc 16 and the holder. The discs can be readily detached by snapping the connector 34 out of the hub socket 20 and attaching a new abrasive disc and connector which are provided as a replaceable unit.

In FIGS. and 6 there is shown a modified form of construction. There is a body 44 comparable in construction to the body 14 of the first embodiment. In the center the body 44, which may be of rubber, is a hub 46 which is preferably of metal. Extending through the center of the hub 46 is a threaded spindle 48 which is axially movable relative to the hub 46. It has an outer end 50 preferably of the same general shape as the outer end of the spindle 22 with the tapered surfaces 52 and 54 separated by a nontapered squared surface 56.

The hub 46 has a tapered socket 58. In the inner or smaller end of the socket 58 is a squared groove 60 and at the larger or outer end of the socket is a radially i11- wardly disposed rib 62.

A relatively stiff yet resilient plastic connector, indicated generally at 64, has a wide disc or flange portion 66 with inwardly extending detents 68 which may be 2 or 4 in number. They are receivable in sockets 70 in the outer face of the plastic body 44. The connector 64- has an inwardly extending sleeve 72 whose outer surface has a taper 74 conforming generally to the taper of the hub socket 58. The inner wall of the sleeve 72 has a squared portion 76 and an inwardly tapered portion 78, the latter conforming in angularity to the taper 52 of the spindle 48. The inner end of the sleeve 72 has an outward rib 80 which is receivable in the groove 60 in the hub 46. A nut 82 is threaded on the spindle 48.

An abrasive disc is adapted to be adhesively secured to the outer flange 66 of the connector in the same manner as the securing of the disc in the first described embodiment. The connector is slipped over the outer end of the spindle 48, the sleeve portion 72 of the connector being split as in the case of the connector 34 of the first enrbodiment so that the portions of the sleeve 72 defined by the split or splits as desired, permit the sleeve 72 to slip over the enlarged outer end of the spindle 48. The connector 64- is pressed into the hub socket 58, connector head 80 being received in hub groove 60 and hub head 62 being received in a groove 84 formed in the connector just behind the flange 66. Then the nut 82 is drawn up on the spindle 48 to pull the outer end of the spindle and connector tightly into the hub socket or recess '58.

From the foregoing it will be seen that I have provided an abrasive disc holder which will securely retain the disc attached connector portion in the hub of the holder against accidental removal and against relative movement 4 of the disc and holder. The construction is one which is readily adaptable to cast or molding so that the parts can be duplicated at a reasonable cost and wherein abrasive discs can be replaced quickly and easily.

It should be understood that various changes can be made in the form, details, arrangement and proportions of the various parts without departing from the spirit of the invention.

I claim:

1. An abrasive disc holder comprising a disc supporting a body having an outward disposed disc engaging face and including a central hub, a spindle extending from said hub and having a portion in spaced relation to a portion of the hub, said hub having an inwardly tapered wall facing said spindle portion, one of said hub and spindle portion having an inwardly facing abutment, and a connector having means for engaging an abrasive disc and having a portion receivable between said hub and said spindle portion and behind said inwardly facing abutment and shaped to provide an inward wedging action supplemented by working pressure on the abrasive disc.

2. The structure in claim 1, wherein said connector portion is receivable between the hub and spindle portion having a taper at an angle approximating that of said hub portion.

3. The structure in claim 1, and said spindle portion having a locking groove adjacent its outer end, and said connector including a pair of spindle portion engaging elements, at least one of which is yieldably movable toward and away from the other, said spindle Portion engaging elements being expansible insertable over the end of said spindle portion, and at least one of said spindle engaging elements having a portion receivable in said locking groove.

4. The structure in claim 1, and the tapered portion of said hub spaced from said spindle portion comprising a frustrum of a pyrimid, and a portion of said connector receivable between said hub and said spindle portion comprising pyrimidal frustrum.

5. The structure in claim 1, and the outwardly disposed disc engaging face of said body and said connector having interengaging portions preventing rotation of said disc relative to said body.

References Cited UNITED STATES PATENTS 2,991,596 7/1961 Walters 51-376 3,239,971 3/1966 Freerks et a1. 51379 3,270,467 9/1966 Block et al. 51358 3,270,468 9/1966 Block et a1. 51358 OTHELL M. SIMPSON, Primary Examiner. 

